In the first 4 months since the U.S. Supreme Court signaled executions may continue on the country's 3,200-strong death row, at least 2 inmates will have jumped the queue after convincing judges that they were competent to drop their appeals and seek speedy executions.

On Jun. 6, David Mark Hill was executed in South Carolina after "volunteering" for a quick end to his life. He had spent 8 years on death row after being convicted of shooting 3 social workers. Death row inmates can normally expect to wait at least 12 years before their execution.

Hill was the 6th person to be executed since April when a temporary country-wide moratorium was lifted after the U.S. Supreme Court ruled lethal injection, the main means of state killing in the U.S., was not in violation of the constitution.

On Aug. 14, Michael Rodriguez, also a "volunteer", will be executed in Texas after dropping his appeals. If his execution goes ahead, Rodriguez will have spent only 6 years on death row.

The 2 cases are focusing attention on how judges decide when death row inmates are competent enough to drop their appeals and apply for a speedy execution date.

Since capital punishment was reinstated in the U.S. in 1976 after almost a decade, 130 inmates have "volunteered" to be executed before exhausting all appeal rights. This represents 1 in 10 of the more than 1,100 executed in the U.S. in this period. 5 of the 14 states which resumed executions after 1977 -- Connecticut, Idaho, New Mexico, Oregon and Pennsylvania -- have yet to execute a "non-volunteer".

"(More than) 75 percent have a documented history of mental illness," John Blume, a professor of law at Cornell Law School and a leading expert on "volunteers", told IPS. "Many are very mentally ill with a high incident of schizophrenia."

In a recent study of most of these "volunteers", Blume found 14 were diagnosed schizophrenics. Many suffered from other severe mental disorders. At least 30 had previously attempted suicide.

In 2002, the Supreme Court ruled that executing mentally retarded criminals was a violation of the Eight Amendment outlawing cruel and unusual punishment. But so far there has been no Supreme Court examination of the level of mental health required to "volunteer" for an execution.

"Mental retardation is not thought to be treatable, while most mental illnesses are highly treatable," Mark Heyrman, a clinical professor of law at the University of Chicago, explained to IPS.

But it was often a "procedural nightmare" to assess whether serious mental illness was hindering an inmate from seeking his criminal justice rights.

Hill appears to have had many of the mental health characteristics of numerous other "volunteers" studied by Blume.

In the months before his crimes, Hill was being treated for 3 serious mental disorders. He had also made a number of suicide attempts, according to Amnesty International.

When he was brought to trial in 2000, a doctor testified that he had suffered brain damage after trying to shoot himself after the killings.

But in 2007 when "volunteering" for execution, a psychiatrist testified that Hill's past mental disorders were in remission and he had recovered from his brain damage.

A judge found Hill, who had expressed remorse and apologised to the families of his victims, was competent to waive his appeals. This decision was upheld by the state's Supreme Court on Apr. 28.

"Someone who is severely mentally ill can be deemed competent and allowed to represent himself or waive appeals," Blume commented on such cases, adding that the main problem was setting a standard for "competency".

No one knows how many "volunteers" are waiting to follow Hill and Rodriquez into the death chambers.

"A number of attorneys have told me that during the long course of appeal representation it is very common for their client to give up for a short time and then later go back to their appeal," Richard Dieter of the Death Penalty Information Centre (DPIC) told IPS.

"So the number of people on death row who temporarily become volunteers is probably great, but there's probably no way to count them," he said.

Hill was one of those who changed his mind a month after first requesting his execution in May 2007. But in July 2007, he reverted to his original decision.

"Volunteers" typically give several reasons for waiving their right of appeal, Ronald Tabak, a New York based lawyer familiar with metal health issues in capital punishment cases, told IPS.

They may often say they are tired of the appeal process and feel execution is inevitable. They sometimes argue that their death will give solace to a victim's family and be an atonement for their crimes.

"The problem is, these are rationalistations from a person with mental illness," Tabak said, adding that if such defendants received proper medical treatment they might want to continue their appeals, and in some instances have winning legal claims.

The DPIC cites the years waiting on death row as a contributing factor in pushing many to drop pending appeals.

On death row they are isolated from other prisoners and excluded from prison programmes. They spend as much as 23 hours a day in their cells and have restricted visitation rights. Such conditions lead to what is sometimes called "death row syndrome".

Death row inmates can become suicidal, delusional and insane. Inmates who were mentally ill before may become even sicker, according to the DPIC.

Their views suggest that one of the next major legal challenges to the death penalty in the U.S. may be directed at both the constitutionality of executing people exposed to "death row syndrome" and allowing death row inmates with a record of past mental illnesses ever to sign away their full rights to appeals.